Treatment of hydrocarbon oils



Patented Apr. 29, 1941 TREATMENT OF HYDROCARBON OILS Lyman C. Huff, ChicagoJll., assignonto Universal `Oil Products Company, Chicago, Ill., a corpora.

Y tion of Delaware Application-August 28, 1937, Serial'No. 161,403

` (cl. 19e-11) 3 Claims.

This is a continuation-impart of my Ycio-pending application Serial No. 113,424 which Wasiiled on November 11, 1936.

The invention relates to an improved method of fractional distillation which is particularly idirected to the efficient and economical separation of hot vaporous hydrocarbons, such as those resulting from the pyrolytic conversion of hydrocarbon oils, into selected heavy fractions boiling above the range of gasoline, selected high-boiling A.

drawing which illustrates one 4specific form of.

apparatus in which the process may fbe conducted. The novelty and advantages of the invention will be moreapparent from-the following description of the drawing.

Relatively hot vaporous hydrocarbons, such as those resulting from the pyrolytic conversion tof hydro carbon oils to produce therefrom highyields of good quality gasoline, are ,suppliedfrom any desired type of cracking system, `not illustrated, through line I and valve 2 to fractionator `3 wherein their high-boiling fractions, ypreferably comprising substantially -all of thecomponents of the vapors boiling above the range of ,thedesired gasoline product, are condensed as reflux condensate. lSuitable fractionating means, notillustrated, such as bubble trays, packing, perforated pans or the like or any desired combination of such well known means, are provided 'in fractonator 3 and preferably one or more relatively cool liquid hydrocarbons is supplied, as vwill Abe later described, to thefractionator to directly commingle therein with the vaporous vproducts undergoing fractionation and serve as a cooling and reuxing medium.

The total reflux condensate vformed Vin fractionator 3 or selected relatively heavy :fractions thereof may be .removed from the lower portion of this zone through line 4 `and valve ,f5 andmay be recovered, after cooling .by well `known means, not illustrated, as a final product ,of the process or may be directed, by well known means, not shown, to any desired further treatment `such as, for example, further cracking in the same-cracking system from which theheated vaporollaproducts subjected to said fractionation `are derived, or in separate cracking apparatus of any desired form, not illustrated.

Incase i-t is desired to separate the reflux condensate formed in fractionator 3 into selected fractions of different 'boiling characteristics, this maybe accomplished within the fractionator by removing only high-boiling fractions of the reflux condensa-te from the lower portion of this zone, as above described, and separately removing one vor more selected lower boiling fractions fromr one or a plurality of suitable intermediate points in the fractionator. vLines 6 and valves l are provided for this pmpose in the case here illustrated and a selected relatively low-boiling fraction or fractions thus removed from the fractionator may -be cooled Vby well known means, not illustrated, and recovered as fa final product of the process or subjected to any desired further treatment either Within the cracking system from which the vaporous products subjected -to said fractionation are derived or in a separate system of any desired type.

The invention provides for introducing hydrocarbon `oil charging stock for the cracking operation from which the vapors subjected to said fractionation are derived into fractionator 3 at any desired point or plurality of points in this Zone by means of line 8 and branch lines 9 and l0, controlled, respectively, by valves Il and I2. By this method of operation, a regulated portion or all of the charging stock is directly commingled with the relatively hot vaporous products undergoing fractionation, serving to partially cool and assist said fractionation of the vapors. Also, by this method of operation, any components of the charging stock boiling within `the range of the desired overhead vaporous product from fractionator 3 will be vaporized and commingled with the vaporous conversion products of like boiling characteristics, while the higher boiling components of the charging stock will commingle with the reux condensate formed in fractionator 3 and, when the latter is separated into selected low-boilingand high-boiling fractions, the charging stock is also ksubjected to the same separation.

Fractionated vapors of the desired end-boiling point, which include normally gaseous products `and materials boiling within the range of the desired gasoline product of the process, and which may, when desired, also include somewhat higher boiling materials such as heavy naphtha fractions, kerosene, 4kerosene distillate, pressure distillate bottoms, or the like, are removed from the upper :portion `of fractionator 3 `and ldirected through line I3 and valve I4 to further fractionation, as Will be later described, in fractionator I5.

In order to provide a suitable light refiuxing and cooling medium for use in the upper portion of fractionator 3, a regulated quantity of the fractiona-ted vapors removed from the upper portion of this zone are directed from line I3 through line I6 and valve I1 to cooling and partial condensation in condenser I8. The resulting uncondensed gases and the uncondensed 10W-boiling fractions of the vapors supplied to condenser I8 are directed therefrom through line III and valve to collection and separation in accumulato-r 2 I. Distillate CII collected in accumulator 2| is Withdrawn therefrom through line 22 and valve 23 to pump 24 by means of which it is recirculated in regulated quantities through line 25 and valve 26 to the upper portion of fractionator 3 whereinA it serves as a cooling and reuxing medium for maintaining the desired Vapor outlet temperature from the fractionator and controlling the end-boiling point of the overhead vaporous stream from this Zone. The vapors and gases which remain uncondensed in accumulator 2| are removed therefrom Ithrough line 21, either alone or together with any distillate collected in this Zone in excess of that required as a cooling and refluxing medium in fractionator 3, and this materi-al may be directed from line 21 through line 28 and valve 29 to further fractionation in fractionator I5, or, in case only uncondensed vapors and gases are removed from accumulator 2| through line 21, they may, when desired, be directed through valve 3U in line 21 to further `cooling and partial condensation in condenser 44, the function of which Will be later described, or, they may be directed from line 21 through line 3l and valve 32 to further cooling and condensation in subcoolers 51 and 51', which will be later described.

The vaporous and gaseous materials supplied to fractionator I5, as previously described, Vare further fractionated in this zone to separate the same into low-boiling vaporous components, consisting of light gasoline fractions of the desired end-boiling point and normally gaseous products, Y

and a higher boiling condensate comprising heavy gasoline fractions and, when desired, also including somewhat higher boiling materials such as previously mentioned.

In order to substantially free the reflux condensate formed in fractionator I5 of dissolved normally gaseous products and light fractions boiling Within the range of the desired overhead vaporous product from fractionator I5, said reflux condensate is preferably reboiled either within or external to fractionator I5 in any well known manner such as, for example, by the introduction of steam or by passing this reux condensate in indirect heat exchange with a suitable heating medium such as steam or, preferably, relatively hot oil, oil vapors or gases derived from Within the cracking system. -In the -condensate thus removed from fractionator I5 comprises, as previously mentioned, high-boiling gasoline fractions and due to the fairly high temperature at which this material may be recovered from fractionator I5 and the fact that it may be substantially freed of entrained gases and undesired low-boiling components by simple reboiling, these heavy gasoline fractions will not require stabilization to reduce their vapor pres-v sure but' may require chemical treatment to reduce their sulfur content, gum content and/or .improve their color or gum, color and antiknock stability. Any such further treatment of these high-boiling gasoline fractions is definitely within the scope of the invention, although it is not concerned with the specific method whereby they are furthertreated and the latter is, therefore, not illustrated. 'The invention also contemplates reforming "of the heavy gasoline fractions recoveredl from fractionator I5 in case the same are'of unsatisfactory antiknock value, this being accomplished b-y subjecting the heavy Vgasoline -fractions to cracking. conditions of high temperature at substantial superatmospheric pressure regulated to materially improve the Vantiknock.characteristics of the gasoline fractions Without excessively altering their boiling range. When reforming of the heavy gasoline fractions is required, the vaporous products supplied from fractionator `3 to fractionator I5 may, vwhen desired, include materials such as previously mentioned, boiling somewhat above the range of gasoline, whichV higher boiling materials are susceptible to further cracking under conditions suitable for reforming of the heavy gasoline fractions to produce additional yields of good Vquality gasoline from said heavier fractions.

reforming step, not illustrated, together with the high-boiling gasoline fractions.

Fractionated vapors of the desired end-boiling point, which consist. of normally gaseous products and light gasoline fractions, are directed from the upper portion of fractionator I5 through line 42 and valve 43 to cooling and partial condensation in condenser 44. The resulting distillate anduncondensed vapors and gases are directed from condenser 44 through line 45 and ,valve'45 to'collection and separation in accumuu lator 41. The distillate collected in accumulator 41 is returned in regulated quantities by means of line 48, valve 49, pump 50, line 5I and valve 52 tothe upper portion of fractionator I5 wherein it serves as a cooling and refluxing medium for assisting fractionation of the vapors and mainvtaining the desired vapor outlet temperature from the fractionator, thus controlling the endboiling point .of the light gasoline product recovered from fractionator I5.

The vapors and gases remaining uncondensed vin accumulator 41 are removed therefrom, either alone or together With any distillate collected in this Zone in excess of that required as a coolingV vand reuxing medium for fractionator I5, and, 4in thecase here illustrated, lthis material is directed from accumulator 41 through line 55 and 'valve 56 to and throughsub-coolers 51 and 51 wherein it is cooled to a lower temperature than 'that employed incondenser 44 whereby to condense substantially all of its normally liquid components.l Although two sub-coolers are illustrat- "ed'in'the drawing, one or any desired number of 'ap'lural-ityof' such zones may be employed 'and `aeaacct valve 6l to sub-cooler 51 wherefrom it is discharged through line 62 and valve 3. The materials undergoing cooling and condensation pass, in the case here illustrated, through sub-coolers 51 and 51', in series, counter-current to the general direction of now of the cooling medium through each of these zones, line 64 containing valve B being provided for transferring the materials cooled and partially condensed in subcooler 5l to further cooling and condensation in sub-cooler 51'.

The distillate and uncondensed normally gaseous products resulting from the cooling and condensation accomplished in sub-coolers 51 and 51 are directed from the latter zone through line 66 and valve t1 to collection and separation L .in receiver iid.

The uncondensed gases which remain undissolved in the distillate are released from receiver E58 through line 69 and valve 10.

The distillate collected in receiver 68 will ordinarily contain a substantial quantity of dissolved normally gaseous `products in excess of those required to produce a distillate of the desired vapor pressure. This light gasoline product is, therefore, preferably subjected to stabilization for the purpose of reducing its Vapor pressure to the desired degree by liberating any excess of dissolved gases therefrom. This is accomplished, in the case here illustrated, by removing the distillate from receiver 68 through line 1| and valve 12 to pump 13 by means of which it is directed through line 1li, valve 15, heat exchanger 16, line 11 and' valve 18 to stabilizer 19, the `operation of which will be later explained.

The purpose of heat exchanger 16 is to reheat and partially vaporze the distillate prior to its introduction into the stabilizing column, this being accomplished by passing the distillate in indirect heat exchange `with a suitable heating medium comprising, for example, steam, hot oil or oil vapors or gases either from within the system ,or from an external source. The heating medium is supplied to heat exchanger 16, in the case here illustrated, through line 8|! and valve 8| and is removed therefrom through line 82 `and Valve 83.

It will, of course, be understood that any other Well known method of reheating and partially vaporizing the distillate to be subjected to stabilization, prior to or after its introduction into the stabilizing column, may be employed within the scope of the invention.

Stabilizer 1Q may comprise any well known form of stabilizing equipment and, in the case `here illustrated, it is a column provided with bubble trays, packing or the like, not illustrated, whereby eicient contact between the ascending vapors and gases and the descending liquids is accomplished.

Preferably, only a portion of the heat required for stabilization of the distillate is accomplished in heat exchanger 16, the remainder being provided by supplying heat from an external source tothe liquid accumulating in the lower portion of the stabilizer by any well known means, not illustrated, or by reboiling this liquid in a reboiler external to the main stabilizing column. In the case here illustrated, the liquid to be re- `boiled is supplied from the lower portion of column 19 through line 86 and valve 81 to reboiler -88 wherein it comes in indirect heat exchange through closed coil 8s in reboiler 88,1the heating medium being supplied to coil 89 through line @il and Valve 9| andl discharged therefrom through line 92 and Valve 93. The vapors and gases evolvedyfrom the distillate by reboiling in reboiler 88 are rreturned therefrom through line 94 and valve S5 to stabilizing column 19. The reboiled distillate comprising light gasoline fractions stabilized to the desired vapor pressure is removed from reboiler 33 through line $15V and valve 91 to cooling and storage or to any desired further treatment and regulated quantities of this material may, when desired, be utilized as the heating medium in heat exchanger 16, the hot reboiled distillate being directed to heat exchanger 16 from reboiler 38 by well known means, not illustrated.

Preferably, to assist in establishing equilibrium conditions in stabilizer 1S and provide a liquid refluxing medium in this zone by condensing vaporous products in the upper portion thereof, suitable cooling means are provided inthe upper portion of the stabnizing column, In the case here illustrated, such cooling means comprise a closed coil d8 through which any desired cooling medium may be circulated, the latter being supplied to coil 93 through line 99 and valve ill and removed therefrom through line lill and valve |62. The normally gaseous products liberated from the distillate and remaining uncondensed in the stabilizer 19 are released from the upper portion of this zone through line m3 and valve |64 and may be directed therefrom to absorption, storage or elsewhere, as desired.

The stabilized light gasoline fractions recovered from the stabilizing step, as previously described, may, when desired, .be subjected to chemical treatment or purification for the purpose of reducing their sulfur and/or gum content or improving their color, gum and antiknock stability. Any such further treatment, although not illustrated, is within the scope of the invention and one of the numerous advantages of the process herein provided resides in the separate recovery of stabilized light gasoline fractions and a heavier gasoline fraction which does not require stabilization, whereby either of these fractions may be subjected to any desired further treatment in the absence of the other or whereby the two fractions may be subjected to different treatments selected. to suit the particular requirements of each. As a specific example, theheavy gasoline fractions recovered from. fractionator l5 may be treated to improve their color and reduce their gum content by contacting the same in heated liquid state at superatmospheric pressure with a.

suitable porous clay, such as fullers earth or the like, while the light gasoline fractions recovered from fractionator l5 may be stabilized and thence blended, without further treatment, with the refined heavy gasoline fractions to form the final full-boiling-range gasoline product of the process. As another specific example, the reflux condensate formed in fractionator I5 may contain any high-'boiling gasoline fractions which are of unsatisfactory antiknock value and may also include some heavier fractions boiling up to approximately 520 F., for example, this reflux condensate being subjected to reforming conditions of high cracking temperature and superatmospheric pressure regulated to produce high yields of good antiknock gasoline, the latter being `subjected to stabilization in column 19, together with the low-boiling gasoline fractions of satisfactory .antikn'ock value separately recovered from fractionator I5 and the resulting stabilized gasoline being recoveredas the nal motor fuel product of the process which may, when required, be treated with an inhibitor, such as relatively small quantities of wood tar fractions, to prevent deterioration of its color, gum and antiknock characteristics.

As a special feature of the invention, in addition to the treatment, as previously described, of the vaporous conversion products supplied to fractionator 3 through line I and valve 2, the system may be utilized for the simultaneous and similar treatment of light hydrocarbon oil distillate from an external source, consisting of or containing a substantial quantity of gasoline or gasoline fractions. This distillate may be, for example, straight-run gasoline or naphtha, gasoline or pressure distillate from a separate cracking system or any desired combination of such materials. The distillate may be supplied to the system either in preheated or relatively cold state and may be introduced either into fractionator 3 or into fractionator l5, although these alternatives are not to be considered equivalent. Provision -is made in the case here illustrated for directing distillate, such as previously mentioned, from an external source, through line I I wherefrom it may ibe directed into fractionator 3 at any desired point in this zone through one or a plurality of branch lines I I I controlled by valves II2. Provision is also made in the apparatus here illustrated for supplying distillate, such as previously mentioned, from an external source, to fractionator I5 through line II3 and valve II4, the same being introduced intofractionator I5 at any desired point in this zone.

Vhen gasoline or gasoline-containing distillate from 'an external source is supplied, as described, to fractio-nator 3, it may serve to partially cool and assist fractionation of the vaporous conversion products in this Zone and is subjected to fractionation therewith, in the manner previously described. In such cases, the components of the distillate boiling Within the range of the ydesired overhead vaporous product are vaporizfed in fractionator 3 and directed therefrom to further fractionation, in the manner previously described, in fractionator I5, while any higher boiling fractions of the distillate commingle With the reflux condensate formed in fractionator 3 and are recovered or subjected to further treatment, as the case may be', with the total reflux condensate or the reflux condensate fractions of corresponding boiling characteristics.

In case gasoline or gasoline-containing distillate from an external source is supplied, as previously described, to fractionator I5, it may serve to partially cool and assist fractionation of the vaporous conversion products with which it commingles in this zone, any light gasoline fractions corresponding in boiling characteristics to the light gasoline fractions recovered as the overhead product from fractionator I5 being commingled therewith and subjected to the same subsequent treatment, previously described, while any heavier fractions commingle with the reflux condensate formed in fractionator I5 and are recovered or subjected to further treatment therewith.

As a specific example of an operation of the process herein provided as it may be conducted in an apparatus of the character illustrated and albove described: Vaporous products formed by the pyrolytic conversion of hydrocarbon oils and previously separated from non-vaporous residual products of the cracking operation are supplied to fractionator 3 at a temperature of about 750 F. and a superatmospherlc pressure of approximately pounds per square inch. Charging stockfor the cracking operation, which is an oil boiling above the range of gasoline, is preheated by means of heat recovered from the cracking system and introduced into fractionator 3 at a temperature of approximately 400 F. wherein it is separated, together with the condensed high-boiling fractions of the vapors, into light and heavy reflux condensates which are cracked in separate heating coils of the aforementioned cracloing system under independently controlled conditions. A Mid-Continent straightrun gasoline of approximately 400 F. end-boiling point is supplied in part to fractionator 3 and in part to fractionator I5 in each of which zones it serves as a, cooling and refiuxing medium.

Vaporous products having an end-boiling point of approximately 400 F. and including substantially all of the straight-run gasoline supplied to fractionator 3, are removed as the overhead product from fractionator I3. A portion of this vaporous stream is supplied to partial condenser I8 wherein lit is Vcooled to a temperature of approximately 250 F., the resulting condensate being returned in regulated quantities to the .upper portion of fractionator 3 as a cooling and refluxing medium, while the uncondensed vapors and gases of the partial condensation step and the remaining portion of the overhead vaporous stream from fractionator 3 are supplied to fractionator I5 for further fractionation. The quantity of the materials in the overhead vaporous stream from fractionator 3 which is supplied to partial condenser I8, is automatically controlled in response to the temperature of the vaporous stream leaving fractionator 3 by means of a temperature controller (not shown) which actuates valve I'l in line I5, so that no substantial excess quantity of distillate is collected in alccumulator 2i. The quantity of distillate recirculated from accumulator 2| by means of pump 24 to the upper portion of fractionator 3 is automatically controlled in response to the liquid level in accumulator 2l by means of a liquid level controller (not shown) which may either vary the speed of pump 24 or vary the quantity of distillate discharged therefrom to fractionator 3, any excess being returned, for example, to accumulator 2| and the pump operating at a substantial constantspeed.

Y The straight-run gasoline and gasoline conversion products supplied to fractionator I5 are separated by fractionation in this zone into a light vaporous fraction and a higher boiling condensate. The light vaporous fraction consists of substantially all of the normally gaseous components of the materials supplied to fractionator I5 and light gasoline fractions having Van end-boiling point of approximately 260 F., which latter are of satisfactory antilmock value. The higher boiling condensate consists of heavy gasoline fractions boiling between approximately 260 and 400 F. These heavy gasoline fractions are also of satisfactory antiknock value but require chemical treatment to reduce their gum content Land improve their color. The heavy gasoline fractions `are sufficiently free of dissolved normally gaseous products that they do not require stabilization to reduce their vapor pressure.

The fractionated vaporous stream removed from the upper portion of fractionator I5 is cooled inpartial condenser 44 to-atemperature' of approximately 170` F. and reg-ulated quantities of the resulting distillate are returned from accumulator 41 to the upper portion of fractionator I5 wherein they serve as a cooling and reuxing medium. The remainder of the distillate collected in accumulator 41 and the vapors and gases which are condensed in partial condenser 44 are directed to further cooling and condensation in sub-coolers 5l and 51 wherefrom the resulting distillate and uncondensed gases are directed to collection and separation in receiver 68. The light gasoline fractions collected in this zone contain a substantial quantity of dissolved gases and are stabilized, in the manner described, to reduce their vapor pressure to approximately 12 pounds per square inch, as determined by the Reid method, the stabilized light gasoline fractions being blended, without further treatment, with the treated and unstabilized high-boiling gasoline fractions recovered from fractionator l5 to form a 400 F. end-point gasoline which is a mixture of straight-run and cracked products having a satisfactory antiknock value and a vapor pressure of approximately 10 pounds per square inch.

The invention is, of course, not limited to the operating conditions nor to the specific mode of operation specied in the above example, since either or both may be varied considerably, as outlined in the foregoing description of the drawing, without departing from the scope of the invention.

I claim as my invention:

1. In a process wherein hot vaporous products i resulting from the pyrolytic' conversion of hydrocarbon oils and containing a substantial quantity of materials boiling within the range of gasoline are fractionated to condense therefrom fractions boiling above the range of gasoline, the combination of concomitant steps which comprise removing from the zone of said fractionation a vaporous stream consisting essentially of gasoline and normally gaseous products, dividing said stream into two portions of like boiling range and subjecting one of said portions to condensation, returning resultant condensate in regulated quantities to the zone of said fractionation wherein it serves as a cooling and reiluxing medium, further fractionating the other portion of said stream to separate the components thereof into a vaporous fraction, consisting primarily of light gasoline fractions and normally gaseous products, and a higher boiling condensate comprising heavy gasoline fractions,

removing said higher boiling condensate from the second mentioned fractionating step, partially condensing said vaporous fraction from the second mentioned fractionating step and returning resultant condensate in regulated quantities to said second mentioned fractionating step wherein it serves as a cooling and refluxing medium, subjecting the vapors and gases remaining uncondensed by the last mentioned partial condensation step to sufiicient further cooling to condense substantially all of their normally liquid components, separating the resulting distillate and uncondensed normally gaseous products, stabilizing the distillate to reduce its vapor pressure to the desired degree by liberating conl trolled quantities of dissolved normally gaseous products therefrom and recovering the resulting stabilized light gasoline fractions.

2. In a process wherein hot vaporous products resulting from the pyrolytic conversion of hydrocarbon oils and containing a substantial quantity of materials boiling within the range of gasolineare fractionated to condense therefrom fractions boiling above the range of gasoline, the

combination of concomitant steps which comprise removing from the zone of said fractionation a vaporous stream consisting essentially of gasoline and normally gaseous products, dividing said stream into two portions of like boiling range and subjecting one of said portions to condensation, returning resultant condensate in regulated quantities to the Zone of said fractionation, wherein it serves as a cooling and reuxing medium, further fractionating the other portion of said stream in commingled state with distillate from an external source which contains a substantial quantity of both light and heavy gasoline fractions, separating the commingled materials by said further fractionation into a vaporous fraction, consisting primarily of light gasoline fractions and normally gaseous products, and a higher boiling condensate comprising heavy gasoline fractions, removing said higher boiling condensate from the second mentioned fractionating step, partially condensing said vaporous fraction from the second mentioned fractionating step and returning resultant condensate in regulated quantities to said second mentioned fractionating step wherein it serves as a cooling and refluxing medium, subjecting the vapors and gases remaining uncondensed by the last mentioned partial condensation step to suicient further cooling to condense substantially all of their normally liquid components, separating thek resulting distillate and uncondensed normally gaseous products, stabilizing the distillate to reduce its vapor pressure to the desired degree by liberating controlled quantities of -dissolved normally gaseous products therefrom and recovering the resulting stabilized light gasoline fractions.

3. In a process for the treatment of hydrocarbon oils wherein hot vaporous products resulting from the pyrolytic conversion of hydrocarbon oils and containing a substantial quantity of materials boiling within the range of gasoline are fractionated to condense therefrom fractions boiling above the range of gasoline, the combination of concomitant steps which comprise connningling with the vaporous products undergoing fractionation, hydrocarbon oil distillate from an external source which contains at least a substantial quantity of gasoline, removing from the zone of said fractionation a vaporous stream consisting essentially of normally gaseous products and the gasoline components of both said vaporous products and said distillate, dividing said stream into two portions of like boiling range and subjecting one of said portions to condensation, returning resulting condensate in regulated quantities to the zone of said fractionation wherein it serves as a cooling and reiiuxing medium, further fractionating the other portion of said stream to separate the same into a vaporous fraction, consisting primarily of light gasoline fractions and normally gaseous products, and a higher boiling condensate comprising heavy gasoline fractions, removing said higher boiling condensate from the secon-d mentioned fractionating step, partiaily condensing said vaporous fraction from the second mentioned fractionating step and returning resultant condensate in regulated quantities to the second mentioned fractionating step wherein it serves as a cooling and refluxing medium, sufficiently further cooling the vapors and gases remaining duce its vapor pressure to the desired degree by uncondensed by the last mentioned partial conliberating dissolved normally gaseous products densation step to condense substantially al1 of therefrom and recovering the resulting stabilized their normally liquid components, separating the light gasoline fractions.

resulting distillate and uncondensed normally 5 LYMAN C. HUFF. gaseous products, stabilizing the distillate to re- 

